The present invention relates to a fluid-flow restrictor device, and particularly to one producing precise rates of restricted fluid flow. Such devices are used in a wide variety of applications, including drip-irrigation systems wherein irrigation water is supplied continuously at a low rate directly to the root region of the plants, refrigeration systems wherein controlled pressure drops are produced in a refrigerant gas, and medical applications wherein the flow of various fluids is precisely controlled.
Several techniques are used for restricting fluid flow in the known devices. Thus, one technique is to provide a small metering opening which restricts the fluid flow to a precisely metered rate; such devices, however, are very expensive to produce to obtain high accuracy, and moreover they have a very high sensitivity to clogging. Another type of device includes an elongated circuitous pathway, such as a spiral groove or a labyrinth, but even though such devices have a lower sensitivity to clogging, they also tend to have low accuracy, particularly when mass-produced. High-accuracy, for example in the order of microns, is very expensive to attain and difficult to reproduce in mass production in both types of devices. In addition, both types of devices usually require disassembly of their parts in order to permit cleaning of clogging particles, which is frequently not only inconvenient to do, but also increases the down-time of the system in which the devices are used.
An object of the present invention is to provide a fluid flow restrictor device having advantages in some or all of the above respects.